# What are the energy efficiency factors for various types of light bulbs?

**URL:** <https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627>\
**Category:** Factual Questions\
**Created:** [December 11, 2006, 12:42am UTC](https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627 "2006-12-11T00:42:47Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![According\_to\_Pliny](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@According\_to\_Pliny](https://boards.straightdope.com/u/According_to_Pliny)\
**Post date:** [December 13, 2006, 12:00am UTC](https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627/21 "2006-12-13T00:00:32Z")

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I respectfully disagree. My question has been answered. Let it be.

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**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\
**Post date:** [December 13, 2006, 12:15am UTC](https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627/22 "2006-12-13T00:15:47Z")

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[QUOTE=According to Pliny]  
I respectfully disagree. My question has been answered. Let it be.  
[/QUOTE]

Of course you’re welcome to ignore everything I have to say (as you have done so far) and keep hanging on to your misconceptions.

But in case anyone else reading this is interested: The numbers expressed in the above table is “overall luminous efficiency”. To quote the same Wikipedia article, “overall luminous efficacy is a measure of the efficiency of the device with the output adjusted to account for the spectral response curve (the ‘luminosity function’).” Basically, the spectrum is weighted according to how bright each color appears to the human eye, and then integrated and expressed as a percentage of input power. So if a red LED converts 100% of the input energy into 680nm (deep red) light, its “overall luminous efficiency” would not be 100%. It’d be about 5%.

By the way, I already stated above that an ideal 555nm light source is 683 lumen/W, and said you can use it to normalize the “lumen/W” figures. If you do that, I think you end up with the same “overall luminous efficiency”.

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**Author:** ![According\_to\_Pliny](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@According\_to\_Pliny](https://boards.straightdope.com/u/According_to_Pliny)\
**Post date:** [December 13, 2006, 12:24am UTC](https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627/23 "2006-12-13T00:24:15Z")

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Fine. I agree with you 100%. Now can you let it go?

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**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\
**Post date:** [December 13, 2006, 12:34am UTC](https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627/24 "2006-12-13T00:34:00Z")

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(And this is why you shouldn’t overmoderate your own threads.)

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**Author:** ![According\_to\_Pliny](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@According\_to\_Pliny](https://boards.straightdope.com/u/According_to_Pliny)\
**Post date:** [December 13, 2006, 1:10am UTC](https://boards.straightdope.com/t/what-are-the-energy-efficiency-factors-for-various-types-of-light-bulbs/383627/25 "2006-12-13T01:10:54Z")

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Lesson learned.

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